Well apparatus



Jan. 28, 1969 Filed June 16, 1965 FIELJ S. W. PUTCH ET AL WELL APPARATUS Sheet 1 of 5 INVENTORS SAMUEL W. PUTCH LAWRENCE H. ECKERT BY MW ATTORNEY Jan. 28, 1969 5. w. PUTCH ET AL WELL APPARATUS Sheet 2 of 5 INVENTORS SAMUEL W. PUTCH LAWRENCE H.ECKERT ATTORNEY Jan. 28, 1969 s. w. PUTCH ET AL 3,424,477

WELL APPARATUS Filed June 16, 1965 Sheet 5 of 5 INVENTORS SAMUEL VI. PUTCH LAWRENCE H. ECKERT av /d-a United States Patent 9 Claims ABSTRACT OF THE DISCLGSURE A pipe hanger particularly suited for on-bottom suspension of casing in a well with a fluted dog cage carrying radially expandable and contractable dogs for locking the hanger to an outer surrounding pipe, and latching rods extending through the dogs to releasably hold the dogs in contracted position.

The present invention pertains to a well apparatus and more particularly to a pipe hanger for supporting an inner pipe at a predetermined location in an outer pipe.

As is well known, an underwater well can be drilled from a drilling rig on or above the surface of the water. After it is drilled, the surface conductor may be stripped down to the ocean floor and the well temporarily abandoned until the drill rig is moved and a production platform has been built. The surface conductor is then extended back to the surface and a conventional wellhead is mounted on the platform to seal between the several strings of pipe.

A problem arises with this method of installation if an attempt is made to support the inner strings of pipe at the upper end of the surface conductor. In the offshore areas in which these wells are drilled, the water may be from 100 to 500 or more feet deep. It is thus evident that a surface conductor of perhaps 500 feet long and having no lateral support would collapse if subjected to the excessive compressive load that would be applied if subsequent inner strings of pipe were hung from the upper end of the conductor.

It is thus desirable to hang these inner strings of pipe at the ocean floor or at a location where there is sufliciently solid formation to support the weight.

It is an object of the present invention to provide an improved apparatus for supporting an inner pipe at a predetermined location in an outer pipe.

Another object is to avoid the application of undue compressive stress to a long unsupported surface conductor of an underwater well installation.

Another object is to provide a hanger for supporting an inner pipe from a recessed coupling in an outer pipe.

Another object is to hang an inner pipe at the most advantageous location in an outer pipe of an underwater well whether this location be at the ocean floor or above or below the ocean floor.

Another object is to provide a pipe hanger which can be latched in a retracted condition but which is automatically unlatched into a seating condition as the hanger is being installed in a well.

Another object is to provide a pipe hanger which can be retrieved from the well.

These, together with other objects, will become apparent upon reference to the following description and accompanying drawings, in which:

FIGURE 1 is a side elevation, partially broken away, of a well apparatus including a casing hanger embodying the present invention.

FIGURE 2 is a side elevation of the subject casing hanger being lowered with its attached inner pipe through a casing head and outer pipe, the latter being partially broken away.

FIGURE 3 is a side elevation of the well apparatus showing how the subject casing hanger suspends the inner pipe within the outer pipe.

Referring more particularly to the drawings, the casing hanger of the present invention is generally identified by the numeral 10 (FIG. 1). The casing hanger includes a tubular mandrel 12 having a cylindrical lower portion 14 provided with external threads 15 at its lower end. The mandrel also includes a cylindrical upper portion 16 having a diameter greater than the diameter of the lower portion 14 and being provided with internal threads 18 and lower and upper edges 20 and 22. A plurality of elongated splines 25 are provided on the lower portion in circumferentially spaced relation therearound and extend from the lower edge 20 of the upper portion 16 of the mandrel downward along the lower portion to lower beveled ends 26.

The hanger 10 also includes a tubular adapter 30, having a cylindrical shank portion 32 threaded into the internal threads 18 of the mandrel 12, and a cylindrical coupling portion 34 diametrically larger than the shank portion and longitudinally spaced from the upper edge 22 of the mandrel. This coupling portion has an internal landing thread 36 of minimum diameter and an internal re-entry thread 38 of larger diameter than the landing thread. These threads 36 and 38 are of opposite hands, that is for example the landing thread is left-hand and the re-entry thread is right-hand, is being understood that the reverse could just as well be employed.

Further considering the casing hanger 10 (FIG. 1), it includes a tubular dog cage 44 having a cylindrical body 46 circumscribing the lower portion 14 of the mandrel 12 and being provided with an inner cylindrical surface 47 having longitudinal slots 48 which receive the splines 25. Mounted in this manner, the body is axially slidable on the lower portion of the mandrel 12 but cannot rotate with respect to the mandrel. The 'body of the dog cage has circular upper and lower edges 50 and 52, and a plurality of circumferentially spaced ribs 54 project radially outward from the body at the same locations as the slots 48 so as to define lengthwise flutes between the ribs. These ribs have beveled upper and lower ends 55 and flat outer faces 56.

The dog cage 44 also has rectangular, longitudinally disposed windows 62 extending radially through the body and the ribs 54 so as to open both interiorly and exteriorly of the cage. Each window has upper and lower surfaces 64 and 65, and the cage provides a plurality of longitudinally extending bores 67 opening into the windows through these upper and lower surfaces, it being noted that the upper portions of these bores open from the upper end of the cage, whereas the lower portions of these bores terminate just below the lower surfaces. A shear pin 69 extends through the dog cage and the lower portion 14 of the mandrel 12 temporarily and releasably to preclude axial movement of the dog cage on the mandrel.

Hanger dogs are individually positioned in the windows 62, each dog having upper and lower surfaces 76 and 77 respectively slidably engaging the upper and lower surfaces 64 and 65 of their associated windows, an upper downwardly and outwardly declined bevel 80, a hole 82 pocket 84 opening inward toward the lower portion 14 extending lengthwise therethrough, an upper and lower of the mandrel 12. The dogs are thus mounted for movement radially of the cage 44 between seating or hanging positions (FIG. 3) projecting outward from their respective ribs 54 and retracted positions (FIG. 1) located substantially entirely within their respective windows 62 and in which retracted positions their respective holes 82 are in alignment with the associated bores 67 in the cage.

Spring units 86 are provided for yieldably urging the dogs 75 into their seating positions. Each spring unit includes a curved leaf spring 88 positioned between the lower portion 14 of the mandrel 12 and its respective dog 75 and a coiled spring 90 disposed in the pockets 84 and having opposite ends bearing against their associated dog and the opposite ends of their corresponding leaf sping. It is to be noted from FIGURE 1 that each leaf spring has an outwardly bowed intermediate portion bearing medially outward against the dog and upper and lower ends bearing inwardly against the lower portion of the mandrel; in addition, the upper ends, in particular, of these leaf springs are curved slightly outward to permit the entry of the lower beveled ends 26 of the splines 25 behind the leaf springs when the dog cage 44 moves axially upward with respect to the mandrel 12, as will be described subsequently.

A significant feature of the present casing hanger is the provision of a latching mechanism 95 (FIG. 1) for releasably retaining the dogs 75 in retracted positions. This latching mechanism includes a plurality of dog release blocks 96, of generally rectangular shape (FIG. 2), having upper and lower bevels 98 (FIG. 1), a lower end face 99, a flat outer face 100, and a transversely extending dovetail groove 102 intermediate the upper and lower bevels. Shear pins 104 releasably interconnect the blocks and the upper portion 16 of the mandrel 12 thereby locating the blocks in circumferentially spaced positions and at the same elevation about the mandrel in individually vertical alignment with the ribs 54 of the dog cage 44. For a purpose to be described, a spring band 106 encircles the blocks 96 and is slidably fitted in the dovetail grooves 102. The band yieldably urges the blocks against the upper portion 16 of the mandrel 12 and has spaced ends 108.

The latching mechanism 95 also includes a plurality of rigid rods 115 having upper heads 117 individually connected to the lower ends of the blocks 96 and shanks 119 downwardly sida-bly fitted through the aligned bores 67 and holes 82 in the dog cage 44 and dogs 75, it being noted that the rods have lower ends 120 fitting in the lower portions of the bores 67 below the lower surfaces 65 of the windows 62 (FIG. 1), this being the latched position of each rod. The blocks and their attached rods are relatively movable away from the dog cage 44 so as to withdraw the rods from the holes 82 in the dogs 75 (FIG. 3), this being the unlatched position of each rod wherein the dogs are released for movement into their seating positions. The manner in which this relative movement occurs will be described subsequently.

The casing hanger 10 is connected to an inner pipe 130 (FIG. 1) by a fluted guide collar 132 which is threaded onto the upper joint of the inner pipe and also onto the external threads of the lower portion 14 of the mandrel 12. In order to lower the casing hanger 10 and the inner pipe 130 into the Well, a running string 136 is connected to the casing hanger by a landing sub 138. The landing sub has lower external threads 139 threaded into the landing thread 36 of the adapter 30.

With particular reference to FIGURES 2 and 3, the well, in which the subject casing hanger is to be used, includes a casing head 145 (FIG. 2) connected to an outer pipe or surface casing 146, which includes an upper section 148 having an upper edge 150, and a lower section 152 (FIG. 3); the upper section may be several hundred feet long. A coupling 154 is threaded onto the lower end of the upper section and is connected to the lower section by a collar 156. The coupling cooperates with the casing hanger, in a manner to be seen, and for this purpose includes an annular recess 158 having an upper beveled edge 159 and a lower seat 160. Usually the coupling 154 is located adjacent to the ocean floor althrough it could be connected in the outer pipe at positions higher or lower in the hole than the ocean floor. In accordance with the purpose of the invention, however, the

coupling should be located where there is solid formation to support it.

In operation, the running string 136 lowers the casing hanger 10 and inner pipe through the casing head and the outer pipe 146, it being noted that initially the rods 115 are in their latched positions with the dogs 75 being in their retracted positions, as shown in FIG- URE 1. As the blocks 96 descend through the casing head, they eventually engage the upper edge of the casing head and are prevented from moving farther downward since the maximum diameter across the blocks is greater than the inside diameter of the outer pipe. Because of the weight imposed on the mandrel 12 by the inner pipe 130, however, the shear pins 104 break and the mandrel continues to move down relative to the blocks 96. Furthermore, since the dog cage 44 is connected to the mandrel by the shear pin 69, the dog cage also moves down with the mandrel. When the lower end faces 99 of the blocks 96 are above the upper edge 22 of the mandrel 12 (compare FIGS. 2 and 3), the spring band 106 draws the blocks inward against the shank portion 32 of the adapter 30, whereupon the maximum diameter across the blocks is now less than the internal diameter of the outer pipe 146. Therefore, the blocks are free to move downward through the outer casing with the casing hanger 10.

During the above-described relative movement between the mandrel 12 and the blocks 96, there was also relative movement between the dog cage 44 and the rods 115 causing withdrawal of the rods from the cage. When the lower end faces 99 of the blocks 96 are above the upper edge 22 of the mandrel 12, the lower ends 120 of the rods 115 are above the upper surfaces 64 of the windows 62 in the cage 44 so that the dogs are released for movement into their seating positions. Therefore, when the blocks 96 have been drawn inward against the adapter 30 and the blocks move downward with the mandrel within the outer pipe 146, the spring units 86 are urging the dogs outward against the inner surface of the outer pipe.

The outwardly urged dogs 75 slide down along the inner surface of the outer pipe 146 and eventually register with the recess 158 in the coupling 154 whereupon they are urged outward into the recess with their lower surfaces 77 resting on the seat in the recess. With the dogs in seating position within the coupling, further downward movement of the dog cage 44 is arrested. However, the weight of the inner pipe 130 breaks the shear pin 69 and causes the mandrel 12 to move downward relative to the dog cage 44. Thus, the splines 25 slide back of the leaf springs 88 thereby firmly and dependably locking the dogs 75 in their seating positions. When the lower edge 20 of the upper portion 16 of the mandrel 12 comes to rest on the upper edge 50 of the dog cage (FIG. 3), the inner pipe 130 is hung in the well. That is, the mandrel which carries the inner pipe, is supported on the dog cage which, in turn, is supported in the coupling by the dogs 75.

It is to be noted that during downward movement of the mandrel 12 relative to the dog cage 44, the shank portion 32 of the adapter 30 slides downward relative to the blocks 96; the reason for this is that the lower ends 120 of the rods 115 engage the upper surfaces 76 of the dogs 75 thereby precluding downward movement of the rods and the blocks.

After the inner pipe 130 is hung, other operations within this pipe can be conducted. When it becomes time to move the rig at the surface of the water, the running string 136 and the landing sub 138 are rotated to back out the landing sub from the adapter 30. Subsequently, when it is desired to re-extend connections to the surface of the water, the running string 136 is again lowered, but this time a different landing sub, not shown, is attached to the running string for threading into the re-entry thread 38 which can be done by rotating the running string and landing sub in the same direction as that used to back oif the landing sub 138.

If desired, the casing hanger 10 can be lifted upward relative to the coupling 154. In this instance, the running string 136 lifts the adapter 30 and the mandrel 12 relative to the dog cage 44 until the splines 25 are above the spring units 86. Further upward lifting on the casing hanger causes the engaging upper beveled edge 159 and the upper bevels 80 to cam the dogs 75 out of the recess 158 thereby allowing the casing hanger to move upward relative to the coupling.

It will be understood from the foregoing description that the subject casing hanger supports the inner string of pipe at a selected location in the outer pipe, depending on where the recessed coupling is located in the outer pipe. In an underwater well, this recessed coupling is normally located adjacent to the ocean floor or where there is adequate formation to support it so that the surface conductor, which extends from the ocean floor to the surface of the water, does not bear the weight of the inner strings of pipe and is thus not under undue compressive load. This surface conductor will, therefore, support only its own weight.

Although a preferred embodiment of the present invention has been shown and described, it will be understood that various changes and modifications may be made in the details thereof without departing from the spirit and scope of the appended claims.

Having thus described the invention, What is new and desired to be secured by Letters Patent is as follows:

1. In a well apparatus including an outer pipe, an inner pipe within the outer pipe, at mandrel connected to the inner pipe, means for lowering the mandrel and the inner pipe within the outer pipe, a dog-supporting member mounted on the mandrel, and a dog in the supporting member movable transversely of the pipes between an outer position projected outward from the supporting member and an inner position withdrawn from said outer position, means urging said dog toward said outer position, means in contact with said dog for holding the dog in its inner position, said holding means slidably extending through said dog, means responsive to movement of the mandrel through the outer pipe for withdrawing said holdin-g means completely from said dog to release said dog for movement into its outer position, and means on the outer pipe to receive said dog when said dog is in its outer position.

2. The apparatus of claim 1 wherein said dog supporting member provides a window in which said dog is transversely movable, and wherein said actuating means includes a rod slidably extending through said supporting member and dog.

3. The apparatus of claim 1 wherein said mandrel includes an upper portion of predetermined diameter, an adapter having a shank connected to and of a smaller outside diameter than said upper portion of the mandrel, and wherein said actuating means includes a block and means urging and retaining the block against said upper portion of the mandrel, said upper portion and shank being movable relative to the block upon engagement of the block with the outer pipe during movement of the mandrel within the outer pipe thereby to actuate said holding means out of contact with said dog and allow said dog to be received within said receiving means thereby hanging said inner pipe within said outer pipe, said dog, dog receiving means and mandrel being so constructed and arranged that said dog will not move out of said receiving means in said second position.

4. The apparatus of claim 3 wherein there are a plurality of said dogs and blocks and wherein said urging means is a spring band embracing said blocks.

5. The apparatus of claim 3 wherein said holding means is a rod slidably extending through said dog supporting member and dog and connected to said block.

6. In a well apparatus including an outer pipe having an abutment, a coupling connected to the outer pipe and providing an internal annular recess spaced below said abutment; an apparatus for hanging an inner pipe within said outer pipe comprising a tubular mandrel having a lower portion connected to said inner pipe and an upper portion diametrically larger than said lower portion, a dog cage mounted on said lower portion of the mandrel for relative slidable movement thereon between a first position spaced from said upper portion of the mandrel and a second position engaging said upper portion, said cage having a window therein opening both interiorly and exteriorly of said cage, a dog transversely slidably mounted in said window for movement between a retracted position and a position projecting from said cage, means urging said dogs toward said position projecting from said cage, a rod slidably extending through said cage and dog for holding said dog within said cage, said rod projecting from said cage toward said second portion of the mandrel, a block mounted on said second portion of the mandrel for relative slidable movement lengthwise of said mandrel and connected to said rod, means urging the block against said upper portion of the mandrel, and means for lowering said mandrel and inner pipe through said outer pipe to bring said block into engagement with said abutment whereupon said mandrel and cage move downwardly relative to said block and rod to remove said rod from said dog thereby releasing said dog for outward movement, said lowering means being capable of lowerin-g said mandrel until said dog is urged into the recess of said coupling by said urging means whereupon said mandrel moves downwardly relative to said cage until said cage is in its second position and said dogs, recess, and mandrel being so constructed and arranged that said dogs will not move out of said recess in said second position, whereupon said inner pipe is hung within said outer pipe by said dog, cage and mandrel.

7. In a well apparatus including an outer pipe having an upper edge, a coupling connected to the outer pipe and providing an internal annular recess spaced below said upper edge, and an inner pipe extending lengthwise within said outer pipe; an apparatus for hanging said inner pipe within said outer pipe comprising a tubular mandrel having a lower portion connected to said inner pipe and an upper portion diametrically larger than said lower portion, a tubular fluted dog cage circumscribing said lower portion of the mandrel for relative slidable movement thereon between a first position spaced from said upper portion of the mandrel and a second position engaging said upper portion, said cage having a plurality of circumferentially spaced, radially extending windows opening both interiorly and exteriorly of said cage, dogs radially slidably mounted in said windows for movement between positions within said cage and positions projecting from said cage, means yieldably urging said dog into positions projecting from said cage, rods slidably extending through said cage and dogs for holding said dogs within said cage, said rods projecting from said cage toward said second portion of the mandrel, blocks mounted on said second portion of the mandrel for relative slidable movement lengthwise of said mandrel and individually connected to said rods, means releasably precluding said slidable movement of the blocks, a band constrictively encircling said block and resiliently urging the same against said upper portion of the mandrel, the blocks having outer surfaces tangent to a circle whose diameter is greater than the inside diameter of said upper edge of the outer pipe, and means for lowering said mandrel and inner pipe through said outer pipe to bring said blocks into engagement with said upper edge whereupon said mandrel and cage move downwardly relative to said blocks and rods releasing said releasable means and removing said rods from said dogs thereby releasing said dogs for outward movement, said lowering means being capable of lowering said mandrel until said dogs are urged into the recess of said coupling by said yieldable urging means whereupon said mandrel moves downwardly relative to said cage until said cage is in its second position whereupon said inner pipe is hung within said outer pipe by said dogs, cage, and mandrel, and said dogs, recess and mandrel being so constructed and arranged that said dogs will not move out of said recess in said second position.

8. An apparatus for suspending a pipe ina well, including a tubular mandrel adapted for attachment to the pipe; a dog-supporting member mounted on the mandrel; a dog in the supporting member movable transversely thereof and of said pipe between an outer pipe-suspending position projected outward from said member and said pipe and an inner position Withdrawn from said outer position; means urging said dog toward said outer position; means in contact with said dog for holding the dog in its inner position, said holding means slidably extending through said dog; and means responsive to movement of the mandrel through the well for withdrawing said holding means completely from said dog to release said dog for movement intoits outer position to thereby suspend said pipe in said well.

9. Apparatus forhanging a pipe in a well, including a tubular mandrel adapted for connecting to the pipe; a dog cage slidably mounted on the mandrel; dog means mounted in the cage for movement transversely of the mandrel between a retracted position and a protruding position relative to the cage, said dog means adapted when in said protruding position to secure said cage against axialmovement with respect to said well; means urging said dog means toward said protruding position; means for receiving said dog means in said protruding position;

and latching means operatively mounted on the mandrel above the cage and releasably interconnecting said dog means and said cage for retaining said dog means in said retracted position, said latching means including at least one elongate member cooperable with said cage and slidably extendable through said dog means to lock said dog means in said retracted position, and means cooperating with said latching means responsive to movement of said mandrel through the well for withdrawing said elongate member completely from said dog means thereby to release the same for movement into said protruding position.

References Cited UNITED STATES PATENTS 2,035,834 3/1936 Penick et a1. 285141 2,410,589 11/ 1946 Segelhorst 285-145 2,729,293 1/1956 Cloud 166ll8 2,862,560 12/1958 Bostock ct a1 285-14O 3,090,438 5/1963 Raulins 166-75 3,099,317 7/1963 Todd 285-39 CARL W. TOMLIN, Primary Examiner.

DAVE W. AROLA, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,424 ,477 January 28 1969 Samuel W. Putch et a1 It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 65, cancel "extending lengthwise therethrough, an upper and lower" and insert the same after "82" in line 63, same column 2. Column 3, line 39, "sidably" should read slidably Signed and sealed this 14th day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

